The present invention relates to drain valves and, more particularly, to drain valves used in fuel tanks or the like. However, the valves could also be used for various other purposes in connection with confined fluids.
Drain valves are often provided on aircraft fuel tanks so that liquid within the tank may be readily removed or drained. Such drain valves typically include a drain port or opening through which the liquid in the tank is drained and a valve member or poppet which moves axially in relation to the port in order to open and close the port.
One difficulty encountered with drain valves of the type described above is that a seal used in conjunction with the valve member for closing the drain port will deteriorate over a period of time and require replacement. To aid in the replacement of the seal, prior drain valves have included features, such as those disclosed in U.S. Pat. No. 3,698,420, issued to Douglas Grundy et al, and in U.S. Pat. No. 3,703,189, issued to Floyd G. Koller, that permit the valve member to be moved to an accessible position below the drain port so that the seal on the valve member can be removed and replaced without removing and disassembling the entire drain valve.
A problem associated with prior drain valves of the type shown in the aforementioned Grundy et al and Koller patents is that considerable complexity is encountered in the manufacture and assembly of the drain valves in order to permit the valve member to occupy several positions in relation to the drain port. Such complexity increases the difficulty of manufacture and the cost of the drain valves.